Extended play videodisc

Abstract

An extended play videodisc and a method and apparatus for playing it. The disc carries every m th segment of a video program and the segments are repeated m times to approximate the original program. Prior art extended play discs have contained every other frame or every third frame of video, but the repeating of an entire frame results in poor motion reproduction and flickering scene transitions. The present invention preferably includes the repeating of a field of video an odd number of times. The fields are preferably arranged in order on the disc with n fields per revolution, the disc being rotated such that a new field is read every one and 1/n th revolution of the disc. The new segment is preferably read during the final repeating of the previous segment.

We claim: 
     
       1. A method of displaying video information recorded on a storage medium, comprising the steps of: a. reading a first segment of video information from the medium during a first period of time;   b. repetitively outputting the first segment of video information during a predetermined number of consecutive second periods of time, each of said second periods of time being longer than said first period of time;   c. reading a further segment of video information from the medium simultaneously with a portion of the last of the predetermined number of second periods of time during which the first segment of video is being outputted; and   d. functionally repeating steps b and c for each video information segment read.   
     
     
       2. The method as claimed in claim 1, wherein said reading steps include the step of storing the video information at a first rate and said outputting step includes the step of recalling the stored video information at a second rate which is slower than the first. 
     
     
       3. The method as claimed in claim 1, wherein said storage medium is a videodisc having substantially circular concentric tracks of video information thereon, and said reading steps include scanning a portion of one of the tracks of the disc, the rate of scanning being chosen such that the output time for a segment of video information which output time is equal to the predetermined number of times the segment is outputted times the length of each of the second periods of time, is also equal to the time required to scan all of the segments of video information in one substantially circular track plus one additional segment of video information. 
     
     
       4. The method as claimed in claim 3, wherein a segment is a field of video information, each field is output three consecutive times, and each track of the disc includes four fields of video information, five fields of information being scanned during the time required to output a field three times. 
     
     
       5. The method as claimed in claim 4, further comprising the step of initially recording every third field of a video program on the storage medium. 
     
     
       6. Improved long play videodisc, comprising a disc base of the type suitable for the recording thereon of a plurality of tracks of indicia representing video signals, said disc having recorded thereon a plurality of fields of video signal in each track, each field being noncontiguous with each of the fields adjacent thereto along the track. 
     
     
       7. The videodisc as claimed in claim 6, wherein there are n fields of video recorded on each track of the disc and the fields are every m th field of a video program, the video signals and video sync signals being recorded at (n+1)/m times their standard speed. 
     
     
       8. The videodisc as claimed in claim 6 or 7, wherein there are four fields recorded in each track of the disc and the fields are every third field of a video program. 
     
     
       9. Improved long play videodisc playback apparatus, for playing a videodisc having recorded thereon a plurality of tracks, wherein a plurality of fields of video is recorded in each track, each field being noncontiguous with each of the fields recorded adjacent thereto, comprising: means for reading said recorded video fields from said disc;   memory means for storing video signals;   means for storing said read video fields individually in said memory means;   means for recalling said stored video fields from said memory means, said recalling means recalling said stored video fields from said memory means repeatedly a predetermined number of times, said storing means beginning storing the next field of video prior to the completion of the last recalling of a field.   
     
     
       10. The playback apparatus as claimed in claim 9, further including means to rotate the videodisc such that said means for reading passes over an entire track of the disc plus one field during the time that a single field is being repeatedly read from said memory means. 
     
     
       11. The playback apparatus as claimed in claim 10, wherein said recall means recalls stored video fields at a slower rate than said means for storing stores the video fields. 
     
     
       12. The playback apparatus as claimed in claim 11, wherein said means for reading and said means for storing are active only during a portion of the final recalling of a field. 
     
     
       13. The playback apparatus as claimed in claim 12, wherein each track on the disc includes four fields and said reading means reads every fifth field to thereby read each field in order and at intervals of one and one-quarter revolutions of the disc. 
     
     
       14. The playback apparatus as claimed in claim 12 or 13, wherein said means for recalling recalls each field three times over a period equal to one and one-quarter revolutions of the disc. 
     
     
       15. The playback apparatus as claimed in claim 9, wherein: said memory means is a digital signal memory;   said means for storing includes an analogue to digital converter and means for clocking the digital signal into the digital memory at a first rate; and   said means for recalling includes a digital to analogue converter and means for clocking the digital signal out of the memory at a second rate, said second rate being slower than said first rate.   
     
     
       16. The playback apparatus as claimed in claim 9 for playing discs having n fields per track, further comprising means for activating said means for reading and said means for storing for only 1/n th of the period of each revolution of the disc and only after each one and 1/n th revolution of the disc, to thereby read and store a new field every one and 1/n th revolution of the disc. 
     
     
       17. The playback apparatus as claimed in claim 9, further comprising: means for selectively recovering a number of separate audio tracks, the number of audio tracks being at least equal to the predetermined number of times each field of video information is recalled from said memory means; and   means for selecting a particular different one of the audio tracks each time a field is recalled from said memory means.   
     
     
       18. A videodisc playback apparatus for playing video information recorded in sequence in a plurality of substantially concentric tracks on a disc comprising: means for sequentially playing contiguously positioned segments of the video information spaced by nonplay periods equal to the period of revolution of the disc;   means for storing a played segment of video information;   means for outputting the stored segment of information a plurality of times for a period of time equal to the period of revolution of the disc plus the time required to read a further segment of video information from the disc.   
     
     
       19. The videodisc playback apparatus as claimed in claim 18, wherein each segment is a video field. 
     
     
       20. The videodisc playback apparatus as claimed in claim 18 or 19, wherein said means for playing and said means for storing play and store a segment of video information in a first period of time, and said means for outputting recalls the stored segment and outputs it during a second period of time which is after said first period of time and longer than said first period of time. 
     
     
       21. A method of displaying video information recovered from a recorded videodisc, wherein the videodisc has substantially circular concentric tracks of video information therein, the video information being recorded along said tracks as a series of noncontiguous fields representing every Nth field of a standard video signal, said method comprising the steps of: a. reading a first field of said recorded information at a first relatively high rate;   b. displaying said first field of recorded information on a video monitor a plurality M of times at a second relatively low rate;   c. reading another field of said recorded information at said first rate before the last of said M times in step b is completed; and   d. repeating steps b and c a number of times necessary to play out a desirable amount of recorded video information.